How to increase your oil pump pressure with 2 washers and 20mins work.
You can buy a new std oil pump for £15 -£20 and increase the spring pressure this way or spend £40 on a pump that is already high pressure, the choice is yours.
Recently I had trouble with a new high pressure pump that was set far too high, 95psi from the factory, I had to strip the engine and fit a std relief spring with 2 washers to lower the pressure to 80psi cold.
To modify a std pump, first drill a 5mm hole in the centre of the relier spring cap, then tap the hole out m6 as square to the pump as you can.
This is done so that you can use a short m6 bolt to pull the relief spring out.
Then use some appropriatly sized washers built up so that you can tighten the bolt and pull the spring cap with little effort.
This method works very well, now get some m8 washers and grind down the outer diameter so that they fit into the spring cap with a little clearance.
Two 1.6mm thick washers (3.2mm thick in total) are the max you will need, this will give you about 75 to 80psi cold oil pressure and 65 to 70psi fully warmed up which is good for 8000rpm.
For reference the std pump has 55psi cold pressure and about 45psi fully warmed up.
Next job is to weld in the 5mm hole you drilled in the spring cap, this can easily be done with either a tig or mig welder.
The important thing is not to hold the spring cap in a vice because when you weld it the combination of the heat and the pressure from the vice would badly distort the spring cap.
The only way to hold it without any risk of distortion is to use a wleders angle magnet, grind off some of the paint for a good earth to the spring cap and the welders earth clamp.
When wleding keep the current pretty low to stop any weld from going down through the spring cap, practice on a piece of 2mm mild steel to get the settings right.
When you have the welder settings correct it is a very easy job.
Grind off the excess weld and it is finnished.
Take the pump apart, remove the 3 rotor housing bolts, the rotors and the take the relief valve out with a magnet.
Clean everything off with petrol and rebuild with plenty of oil.
Fit the two washers into the spring cap. Then carefully tap the spring cap home using a smear of thread lock to help the cap seal into place.
The two washers will compress the spring a little further giving you the increased maximum oil pressure.
Job done.
If you want to check exactly how much oil pressure you will get in the engine, her is how to check it out with air pressure and a 0 to 100psi or more gauge.
This is my contraption below, not the prettiest but it is a very handy tool to have.
You have to pump air into the pressure side of the pump as shown here, then use a T piece for the air pressure gauge.
I use a rubber hose connected to a normal air gun with trigger.
I cut out a plate and welded in a steel pipe, used a small piece of rubber mudflap to seal the joint, it seals perfectly every time.
Next you have to seal off both oil passages inside the pump so that the only place air can escape is out the relief valve.
Before you seal it off, put some oil on the relief valve which can be seen at the bottom of the left oil passage inside the pump.
Another pice of rubber mudflap to seal it off.
A piece of 6mm mild steel to press against the rubber.
Fit the outer rotor.
Fit the end plate and tighten it up.
Connect up the air line.
Stand clear of the oil pickup hole because oil will spray out of it when you open the air line.
Then simply read what the gauge says.
Since air is much thinner than oil you should aim for the hot oil pressure setting,
for example if the gauge says 70psi max air pressure when the oil pump is running in the car is will give about 80psi cold oil pressure and 70psi max when the oil is fully warmed up.
Jason
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